There are existing methods to prepare nanoparticles of compounds.
Nonetheless these known methods do not always allow particle sizes to be reached which are truly of submicron size.
Other known methods do not allow the preparation of large quantities of nanoparticles within reasonable time. The known methods often have reduced production capacities, in particular on account of the difficulties encountered when recovering the particles. Therefore, different methods are known to prepare nanoparticles in a supercritical fluid, applied for example to derivatives of carotenoids (DE-2943267) and to protein derivatives (WO-2006/101352) or for the depositing of nanometric film (U.S. Pat. Nos. 4,734,451, 4,970,093). These documents describe RESS technology (Rapid Expansion of Supercritical Solutions) which is only efficient on a reduced scale and cannot therefore be transferred onto industrial level.
Another method describes the preparation of nano- and microparticles, applied to lipid compounds through the successive use of two supercritical fluids (WO-2007/028421). The first fluid is used to prepare a solution containing these lipid derivatives and the second fluid allows the dispersing of this solution. This method describes the obtaining of nano- and microparticles by modifying the solubility of the lipid composition in the two supercritical fluids.
One of the disadvantages of the methods using supercritical fluids is that they are limited by the solubility of the composition in these supercritical fluids.
In addition, these prior art methods do not allow the preparation of composite nanoparticles with a determined ratio of the composite elements. In fact, the ratio of the composite elements in the initial solution does not correspond to the ratio of the elements of the targeted composite. This difference between the initial ratio and the final ratio of the composite elements results from the respective solubility of the composite elements in the initial solution used and treated with the supercritical fluid.
Also, these methods cannot be universally applied irrespective of the nature of the composition.
The preparation of nanoparticles by misting is also known with the use of transducers (FR-2897281).
Finally, a semi-continuous nanoparticle trapping method is known to purify water and integrates an evaporation step (U.S. Pat. No. 7,628,893).